Abstract

The article presents the results of comparative experimental and computational studies of the acoustic characteristics of the model of a helicopter rotor performed in the modernized test section of the T-1K wind tunnel (WT). In order to identify and minimize the influence of spurious reflections on the studied acoustic characteristics using the Maximum Length Sequence method (M-sequence method) in the T-1K WT, we analyzed the microphone arrangement, which showed that the largest spurious contribution to the measured signal comes from reflections from the WT T-1K wall located behind the microphones. Comparison of the experimentally measured noise levels with the wall raised and lowered confirmed that the wall influences the measured acoustic noise characteristics of the model rotor. Comparison of experimental data with numerical simulation results allowed the conclusion that the WT T-1K modernized wind tunnel is fundamentally suitable to validate numerical methods of calculating the aeroacoustic characteristics of model rotors.

中文翻译：

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测量风洞中直升机旋翼模型的声学特性

摘要

本文介绍了在T-1K风洞（WT）的现代化测试段中对直升机旋翼模型的声学特性进行对比实验和计算研究的结果。为了在T-1K WT中使用最大长度序列法（M序列法）识别并最小化杂散反射对所研究声学特性的影响，我们分析了麦克风的布置，这表明对杂散反射的最大杂散贡献测量的信号来自麦克风后面的WT T-1K墙的反射。将实验测量的噪声水平与上升和下降的壁进行比较，可以确认壁会影响模型转子的测得的噪声特性。